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Goal of this build was to completely replace the stock stereo, but do so with no permanent modifications and nothing visible other than the headunit. Wiring adapters were used whenever possible.

Primary components:

• Stinger Heigh10 headunit
• JL Audio VX1000/5i amplifier + DRC-205 volume control knob
• Illusion Audio C8 component speakers
• OEM non-nav radio cover

Reasons for these:

• I wanted a Stinger Elev8 and ordered one, but it was discontinued and a Heigh10 was delivered. The only real difference between the two is the screen size/style. Excellent audio quality and digital signal direct from my iPhone to the amp. The screen detaches from the electronics, so you can install this without ruining your center console. I think this is the only current non-Chinese head unit with digital output and CarPlay.
• JL Audio VX1000/5i. Digital input + DSP allows rear deck speakers to be used for differential rear fill. They're bandpassed and do L-R. Alternately, I could delete the rear fill and run fully active on the front stage or run C8 woofers in the doors + C3CX (or another similar speaker) in the dash. No potential for ground loops or other noise through RCA cables. Minimum weight and minimal cabling. Super tiny- fits exactly where the stock amp sits.
• Illusion Audio C8 components- I bought these a long time ago. They fit perfectly. The door speakers currently have a 40 hz high pass and sound very nice. The tweeters are a bit hot, but they're set at -0. I may tune them via the crossover, or via the VXi amp.

Wiring

• 15 foot Toslink cable
• 10 ft ethernet cable
• 10 ft usb extension cable
• 4 gauge wire, < 15 ft run directly from amp to battery
• JL Audio XD-MFBW-MAXI fuse box
• JL Audio XD-MAXI-80 80 80 amp fuse
• NVX XRTC4 4 gauge ring terminal
• 22 gauge TXL turn-on wire
• Wire sheathing
• Tesa tape
• Heat shrink

Wiring Adapters

• Metra 99-3018HG dash kit
• Metra ASWC steering wheel adapter
• Metra 40-EU10 radio antenna adapter
• Metra BACKUPCAM-2 rear camera adapter
• 2x sets Metra 72-4568 Speaker Harness adapter
• Metra 70-2057 amp bypass harness
• USB 3.0 and HDMI cigarette lighter adapter

Physical Adapters

• 1/2" HDPE from McMaster for door speaker adapters and amp rack
• 1/4" HDPE from McMaster for amp rack
• 1/2" foam between door speaker and door
• 3/16" rubber foam for between door speaker adapters and factory Bose bracket

+ misc. nuts, bolts, washers.

I installed the electronics where the factory CD player goes. This keeps all of the wiring short and low.

I used the bracket that would normally hold the screen to the electronics box for my mounting adapter. This is then installed using factory mounting bolts.

Some minor trimming of the part of the console which holds the clock is required, to clear the bottom of the screen mounting bracket, but every single screw hole required to mount the clock assembly is still present. The Stinger screen mounting bracket almost perfectly fits into the area in the center (near the Cadillac logo).

This is the bracket that would normally go on top of the electronics box to hold the screen. I used it here by itself. The Metra dash kit brackets did need to be trimmed to clear my not-trimmed factory dash. These screws holding the Metra kit in place were later replaced with the factory bolts. The backup camera adapter is also visible.

The amp in the rear and the crossovers are mounted exactly where the factor amp mounts. The purple, green, grey, brown, etc. wires into the crossover are from the Metra amp bypass kit. All speakers are driven by factory wiring. The power cables shown here run across the lower deck inside the hollow area in the sheet metal directly to the battery on the other side of the trunk.

More pictures and info in the next post.

Tim

 

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The amplifier is mounted on a 1/2" HDPE plate with a 1/4" HDPE plate filling out the hollow areas behind it. It was mocked up with wood first. This layout kept the factory sound deadening felt, ensured all bolts are accessible with all components installed, and provides just enough room and no more to access all connections. The cord with wire sheathing with the ethernet, USB, Toslink, and turn-on wire is the only cable bundle running from the front to the back of the car.
Particleboard template. This came after a construction paper template and before cutting the HDPE.

First layer of HDBP- 1/4" to fill in 1/4" recess in rear panel.

These are the speaker wiring adapters from Metra. I wired them to a spare set of plugs in case I ever wanted to install the factory amp in parallel with this JL amp, but I could have deleted 50% of the wires and run them directly to the crossovers and JL speaker outputs. I got the extra OEM plugs from an amp I bought a while ago. If I did this again, I wouldn't take that extra step and would delete any un-used wiring from these adapters. The X1 connector on the factory wiring does need to be trimmed slightly to fit these plugs, but that doesn't impair its ability to be re-used with the OEM amp.

Front dash and door speaker wires were twisted, sleeved, and heat shrunk and connected directly to the crossovers.

Rear fill wires connected directly between the adapter and the amp wiring harness.

The DRC for the amp was run into the center console into the factory USB + audio area. This was one factory part I had to modify, but replacements are available pretty cheaply. I'll probably buy one just to be safe. Trimming internally is required + enlarging the circular holt to 5/8". I used all three plastic shim washers, but trimmed one side flat so that the knob fit flush against the side of the OEM plastic piece.

Perfect fit into the factory location.

And here's the final solution. The USB cable is the 10' adapter which runs back to the JL Audio VX1000/5i USB cable. They connect under the back seat. The extra length makes it easy to plug into a computer without using an additional cable. I considered using a bulkhead USB connector, but there just isn't room and I didn't want to drill any new holes. The Apple lightning adapter cable is plugged into a cigarette lighter USB + HDMI adapter with 6' cables run directly into the back of the Heigh10 headunit. This is also where I would plug in a USB drive for firmware updates. The JL Audio DCR-205 volume knob does glow, which is one reason I buried it in my center console rather than putting it somewhere else. I didn't want any obvious aftermarket parts other than the screen.

And here's the umbilical cord containing the Toslink, USB, ethernet, and +12V turn-on wire. It runs down the center console from the headunit and the tray above all of the way back to the amp following the path of the factory wiring. It's tiny and pretty well hidden.

 

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Amp power wiring comes down from the hollow part of the rear deck right next to some other wires and tubes. The JL Audio Maxi fuse holder fits directly on the back wall. I used fender washers on the back of bolts to use the existing holes in the plastic cover on the wall beside the battery. The power and ground cables both use factory stud/bolt connections.

The Illusion Audio tweeters were mounted using their included adapters (cut down slightly) + Metra speaker adapters in the factory dash corner locations. The male plug on the factory wiring is slightly different, but plugs in perfectly to the Metra adapter.

The doors got Illusion Audio C8 woofers. They are mounted in 1/2" HDPE adapters that were made with a router + circle jig + jigsaw + drill / countersink.

The factory mounting clip was removed from the speaker wiring adapter and was transferred to the Metra adapter. It was mounted on the back side rather than the front side of the plastic door adapter.

The wiring spring clips on the speakers are too deep and need to be deleted. They hit the door panel and the factory adapter.

They were replaced with machine screws. There is just enough clearance between the woofer and the door adapter with a 1/2" spacer that nothing requires trimming.

After the speaker was installed, some foam was applied around it where it seals against the door. There is a protrusion on the back of the door panel used for alignment before the factory welds the panels together which must be trimmed or else it will touch the woofer's surround. Otherwise, no modifications are needed. Originally the speaker logos were perfectly horizontal, but when I relocated the wiring using the OEM spring clip mount, I had to re-clock the speakers due to the new wire length/position.

 

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Part 4 is TBD. This is a placeholder.
I plan to put a pair of 12's in the spare tire well into a custom fiberglassed enclosure which sits completely below the floor. I believe this will be ~ 2 cubic feet based on some rough calculations. For now, I have removed the factory subwoofer and am using only the C8 woofers for bass. I don't really miss the factory subwoofer, but it's not equal to having a subwoofer.

August 29 edit.
I've decided what to do. I need to move onto other projects, so the fiberglass spare tire well enclosure must wait. I didn't want to go another 3+ weeks without bass and I suspect that it will take me 1 month working a few hours at a time to finish a sub box like this. The front 8's sounds great when not moving, but once driving, I need a lot more bass...
I bought a cheap box off of eBay that has room for 2x 12's. I should be able to install this in a couple of hours. For now, the CTS-V is moving to the back of the garage and my TR6 is moving onto the lift. Once I finish fuel injecting my TR6, I'll come back to the Cadillac and build the planned spare tire subwoofer box. This will give me the chance to evaluate the entire system for a few months, so that if changes are needed, I can make them at the same time.

Custom 08-13 Cadillac CTS Sedan Sub Box Subwoofer Speaker Enclosure (4 door) | eBay

Custom Subwoofer Enclosure for a 2008+ Cadillac CTS 4-door Sedan. 2008+ Cadillac CTS Sedan Sub Enclosure. 2008-2013 Cadillac CTS Sedan Sub Enclosure. Subwoofer Specific Boxes. We have been designing and building custom sub enclosures since 2003.

www.ebay.com

For subwoofers, I did a lot of modeling. I looked at 2x 12's and 1x 15's. Unfortunately, there aren't a lot of great 15's anymore. The ones that do exist are often really deep. I considered Adire Audio Tempest, Gladen SQX Extreme, Image Dynamics ID15, and Sundown SA-15 Classic. The Tempest modeled great, but before I could buy one, they went out of stock for months...
So 12's it is. Same dilemma. The spare tire well is only 9" deep. If you add in excursion, the baffle thickness, and at the bottom of the enclosure, the available depth drops to ~7". If you have a vented pole piece, the subwoofer can only be 6" deep. You can get more if you're willing to have the sub come up above the floor level, but I wanted to maintain a 100% stock look.
I did quite a bit of modeling of Sundown SD-4 D2, Audiofrog GB12D2, Illusion Audio C12 XL, and a bunch of others. These three stood out because they had almost exactly the same response. All were quite a bit better than most of the others I modeled. Keep in mind that with either the eBay box or spare tire box, these are limited to 1 cubic foot each. With the JL Audio amp, I've got 600 W at 2 ohms mono to play with. The constant box size and amp power were a great equalizer. Some of these have enough excursion and power handling to take a lot more power.

1. 2x Sundown SD4 D2 $660 new
   1. 3 dB more at 50 to 80 hz vs. the SI BM MKV
   2. 1200 W / 600 W each appears to max them out in Win ISD and rated for 600 W RMS
   3. 4.6" mounting depth
   4. W type surround reduces front clearance requirement significantly
   5. 14.5 mm linear x-max with suspension mechanically capable of 2x that.
   6. Lightweight neodymium magnet
   7. $344 from Yardsale (risky)
2. Audiofrog GB12D2 $1200
   1. Models virtually identically to the SD4 at equal power.
   2. 1800 W / 900 W each appears to max them out in WinISD, but rated for 500 W RMS.
   3. 6.67” deep - getting iffy, but could work.
   4. 17.6 mm linear x-max
   5. Some reviews are better than the C12 XL.
3. 2x Illusion C12 XL $2000
   1. Models virtually identically to the SD4 at equal power.
   2. 2000 W / 1000 W each to max them out in WinISD, but rated for 600 W RMS.
   3. 6.14” deep
   4. Slightly less efficient?
   5. Lightweight neodymium magnet
   6. 18 mm linear x-max
   7. Ridiculously good reviews.
      

I really wanted the Illusion C12 XL subs to match my front stage, but I can buy the Yardsale Sundown SD-4 subwoofers plus a complete MaxxECU Race Premium kit for the TR6 for the same price... I decided that the Yardsale Sundown SD-4 subwoofers are cheap enough that there's no harm of trying them and bought them last night. There are limited reviews on them, but the reviews that are out there say that they're a pretty awesome SQ subwoofer and nobody has posted about a Yardsale subwoofer with any actual problems in spite of the disclaimers on the site. This is one of the first times I've looked at a bunch of options and chosen the cheapest, although I'll use that as justification to spend the money I 'saved' to buy other car parts...

 

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Part 5. Amp tuning.
Right now, this is like a start-up tune. I'm hoping to take some better measurements using a UMIK and REW and then export those filters into the JL Software, but for now, this will do. It already sounds significantly better than OEM and there's no funky change in bass level vs. volume.

EQ 3 and 4 are setup to do L-R on the rear fill speakers

No EQ or time alignment has been applied. At this point, I've put a 40 hz high pass on the front woofers and bandpassed the rear fill. They are also down 6 dB and 20 ms delayed vs. the front speakers.

August 28 update:
Pulled out my UMIK yesterday. Will need to get up to speed on REW use to get these tuned. I'm going to take some basic measurements before putting in the subwoofers.

 

[random84]

I love it when a plan comes together!

Sent from my SM-G991U1 using Tapatalk

 

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Oh, and the steering wheel controls work perfectly and the HVAC controls work perfectly. The OEM Bose amplifier is completely removed. The OEM OnStar, phone, and other features are all completely disconnected. I had come up with a plan a long time ago to keep them, but decided that with CarPlay + a good radio + a VXi amp, I have absolutely no use for any of the OEM Cadillac features. Not having them makes everything 10x easier, lighter, and more straightforward.

Tim

 

[Blades1_99]

@timg impressive but way beyond my skill level.

 

[E.Murray]

Looks like a pretty well-thought-out and simple (in a good way) system. Nice! I do audio for a living and have done many serious systems (current car has 3 amps, DSP with DiracLive and an 87 liter horn-loaded sub... in a Miata, lol!). You're using quality components and I love the efforts put in to keep from hacking the car up.
In general, I think you made the right call on the sub brand. I've used all the companies you looked at and Sundown is a good choice when cost is a factor. I had a Sundown 12 in an RX-8 using that same kind of ebay box you posted. Worked great. But... I did it a little different. Instead of cramming 2 12's in there and sacrificing a bunch of low end due to the sealed box and small volume (like .7 cu.ft. each, IIRC), I used one hole for the sub and the other for a PSI high-excursion passive radiator. With the 8's in the door, you don't really need more output at 50-60Hz. You need 30Hz. Lots of 30Hz. And you'll get way more with a passive and double the enclosure volume. Did you model that? In the RX8, I had the SA12 on a JL HD1200 (gain turned down a bit - headroom really is a thing...). With the high-excursion passive in the ebay box, it would vibrate your spleen.
Also, another one worth modelling would the big brother to the ones you just sold. I just bought a SI SQL-12 to try out and am optimistic about it. It will probably sit on the shelf until I get a need for it, but it seems like a well-built driver and actually models better than the Sundown. Should be killer... someday.

 

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Ok. So I had 15 minutes to go do some measurements while my dinner was heating up in the oven... I got into the car and hooked the Stinger Heigh10 to my laptop using HDMI. It automatically started mirroring my screen as soon as I connected. I only had to click the HDMI input on the Stinger homepage to have the headunit display my screen.

Then, I plugged in the amp's USB cable and opened up JL Audio Tun software. It automatically found the VX1000/5i amplifier and opened the current Tun file.

Then, I plugged in my MiniDSP UMIK 1 and opened RoomEQ Wizard (REW). Once again, it automatically found the microphone and loaded the calibration I had previously input. I was able to use the signal generator to play pink noise through my right channel and use the RTA to record it. Since I was connected via HDMI, the signal was transferred digitally from my MacBookPro > Heigh10 > JL VX1000/5i.

Problem 1. Not enough screen real estate for REW and Tun on my laptop screen at the same time. Easily fixed by extending my laptop display rather than mirroring.

Problem 2. My front right speaker was playing pink noise per REW's defaul, but so were my rear speakers. They play anything that exists only on one channel. I fixed that by muting them in the Tun software.

Now, I could record a long average in the REW RTA (real time analyzer) window. After fiddling with the settings, I got a good average, but then ran into problem #3.

Problem 3. PEBKAP. Problem exists between keyboard and chair. Having felt pretty good about myself up until this point, I realized that I had just run out of talent. Or perhaps I should say knowledge. While I've been playing with Room Sim in REW for a long time and reading about others using the other features of REW, I have very little idea how to use it myself. For my first time ever using REW, I feel pretty good, but it's painfully obvious that I have a lot of reading and practicing to do.

Preliminary findings:
You can see that the woofer above is pretty flat down to 40 hz. I have a 24 dB/octave high pass at 40 hz. No subwoofers are currently installed. I'm pretty happy with the woofer's low end extension.

The crossover point between the 8" woofer and the tweeter is around 2 kHz. There is a bit of a dip in this region. From the looks of it, I'm going to be cutting the level on my tweeter quite a bit because it's pretty spicy above 2 kHz. I'm going to start with the level settings inside the passive crossover rather than trying to EQ it out. I would like to have something that gets as close to my desired curve as possible before adding EQ bands.

Tim

 

[E.Murray]

You're now at the place the magic happens. Everybody focuses on what brand they like. "What's the best brand of speakers." That's about 5% of the equation. Install (which includes using the drivers properly, not just how to mount them) is waayyy bigger. But the part that separates the men from the boys is the tuning. It's something that can eat up hours at a time getting everything dialed in, only to realize there's a better approach and you get to start over. It sucks. But it's awesome, too. Because you can take a sound system that makes you cringe (every one of mine when I first install) and, with nothing but your own brain, make it sound incredible.
I started with some videos from Kyle Ragsdale on youtube. He uses Helix software, but it's great for getting the steps in the right order. All DSPs do the same things, so the software isn't all that important. What matters is doing things in an order that makes sense. Time delay, crossover points and slopes, phase, and gains all interact so it's easy to chase your tail. I spent dozens of hours on diymobileaudio.com trying to wrap my head around the subtleties before getting a system to sound decent. From my perspective, crossover is the hardest part. Getting it wrong can create a lumpy response that no amount of EQ can fix.
It sounds like you're using the right tools and starting with a simple enough system that you can get it to sound great with some pink noise time. So many start with some 10 speaker monstrosity and think they'll get it to all play nicely together with an hour on REW.
A couple things to start with. First, I'd turn on a little smoothing. Even 1/6 octave will be fine. It will keep you focused on the important things. In general a high Q dip or rise (high Q = tight and steep) isn't something to focus on unless it's pretty deep. Worry about the overall shape first. Second, you're never going to get perfection in the crossover region from an 8" way off axis and a tweeter. Resist the urge to go beyond what the modelling and individual driver measurements tell you. That driver's door 8 is going to be 45+ degrees off axis, so the physics says it's not going to be smooth to 2k. You'll have some output above that, but boosting it to try to flatten the severe off-axis response will just lead to distortion (REW doesn't distinguish between distortion and good sound - it's all energy to the mic). If you just measure that driver, you'll see the cone break-up as a rise in output in higher frequencies. Likewise, they try to rate tweeters to 2k to match up to a big woofer, but I'll bet the Fs of that tweeter isn't much below 2k (and the rule of thumb to stay above double the Fs). Resist the urge to give the tweeter a shallow slop or, heaven forbid, give it any boost down there. Finally, there will be some things that you can't fix. Don't sweat them. That dip at 500 is probably one of them. That's a cancellation from the center console in most cars. You can boost the daylights out of it there and never get rid of it. So don't try. Pay attention to what the response does when you make an adjustment to learn what you can affect and what you can't.
Ok, that was way longer than I intended. Sorry...

 

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And I just tried -6 dB on the tweeter on the crossovers. IMO, it sounds much better. I would probably be happy with this without further tuning. Here's the measured response from the front right vs. a Whitledge house curve. There are some peaks to be tamed, but overall the response is much closer to the curve. I thought this house curve seemed a bit extreme, but it may be what I'm looking for.

The JL Audio house curve is very similar. Some peaks to be tamed, but the overall slope is similar to the native response of the system with -6 dB on the tweeter crossovers.

Versus a Harmon house curve, a -6 dB tweeter setting is be a bit too tame on the top end. Since I don't know which house curve I will prefer in the end, I'm going to try -4 dB on the tweeters before proceeding and applying any EQ. If I do decide that I prefer the sound of the Whitledge or JL Audio house curves, I can always do that via EQ later.

I've also got an issue with my UMIK 1. I'm pretty sure it's not measuring SPL correctly. I'll need to investigate further. I also need to investigate the sickout at 2 kHz, the crossover point between the tweeter and woofer.

 

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Subwoofers are in. The Concept Enclosures boxes are nice. They could use a bit more glue/sealing in the seams, but are put together well. The Sundown SD4 yardsale subwoofers appear to be in perfect shape. I'm not sure why they were in the Yardsale unless this is a way to do direct sales without violating dealer agreements. Will post some pictures of everything installed once I get the trunk back together. I also need to find a way to anchor the top of the box in place. Initial impressions of the subs are that they get loud and sound very nice. We'll see what happens once I retune the system.

 

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And the subs are now fully in. I put a pair of straps on top of the enclosure to hold it in place. They're attached to the studs that hold the seatback in place. I also completely re-started the tuning process now that the subs are in place. I found out that they needed to have their phase reversed otherwise there was a significant dip at the crossover point. I also went back to 0 dB on the tweeters. The curve below is a JL Audio house curve with no EQ on anything. The car has a couple of significant nulls, but is relatively close to this curve. I'm going

And here it is with 5 minutes of EQ tweaking.

Not sure that this is the house curve I'll keep, but it's a start. The nice thing is that you can have multiple curves and change them with the push of the control knob in the center console. This makes testing a lot easier.

 

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TUN software just got a major upgrade with TUN 4.0. It can now measure and correct from a single window including target curves. Will be interesting to see how it compares with TUN + REW. JL Audio put out a Facebook video to walk people through the product announcement and it's quite good. The MAX looks amazing and brings some really compelling features, but even without it, TUN 4.0 is a massive upgrade.

Discover TüN™ 4.0 - JL Audio’s DSP tuning software

www.jlaudio.com

Special Live Event: TüN™ 4 & MAX™ Reveal

Join JL Audio's Manville Smith and Steve Turrisi for a live reveal and demo of TüN™ 4 and MAX™ Measurement System. Following the presentation, there will...

www.facebook.com

JL Audio "MAX" Measurement System & TuN...

Just saw this in my YouTube notifications and thought I'd share. Premiers 10/21/2021 @ 10am PST/1PM EST. Will have to wait to see what it's all about...

www.diymobileaudio.com

MAX-KIT

MAX Audio Measurement System MAX™ is a professional-grade, dual FFT measurement system with five microphones. It is ideal for general audio system measurements, system tuning with DSP, troubleshooting and testing equipment, and solving OEM integration challenges. MAX™ has many applications in...

www.jlaudio.com

JL Audio has licensed a lot of the good stuff from rational acoustic's Smaart and baked it into TUN:

Smaart v8 New License

Smaart v8 is the industry leading, dual platform (Mac & Windows OS), FFT-Based, audio analysis software. Capable of performing unlimited simultaneous Spectrum, Transfer Function, Impulse Response, and SPL measurements – Smaart v8 is the most fully featured software-based audio analysis program...

www.rationalacoustics.com

If I could do my setup differently what would I change?
Probably starting with a 6 or 8 channel VXi + separate standard sub amp to allow me to run active or run more speakers.

 

[Gratefulkid73]

@timg I want to do this install but it's out of my range of capabilities. Hopefully I can find someone in dallas texas that can install and tune it.. thanks for the write up